Modular glenoid prosthesis

ABSTRACT

A method of assembling a glenoid assembly. The method includes selecting a base from a plurality of bases. At least one of the plurality of bases has a size different than a size of one of the other of the plurality of bases. The selected base is coupled to an articulating member and the selected base is locked to the articulating member via a locking mechanism.

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional application of U.S. patent application Ser. No.12/953519 entitled “MODULAR GLENOID PROSTHESIS and cross reference ismade to the following application U.S. patent application Ser. No.12/953522 entitled “MODULAR GLENOID PROSTHESIS”, both of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a prosthetic glenoid component andparticularly to a modular glenoid assembly for attachment to a glenoidsurface of a scapula to replace a natural socket of a shoulder and toprovide a bearing surface for a head portion of an arm bone or humerus.

BACKGROUND

During the lifetime of a patient, it may be necessary to perform a totalshoulder replacement procedure on the patient as a result of, forexample, disease or trauma. In a total shoulder replacement procedure, ahumeral component having a head portion is utilized to replace thenatural head portion of the arm bone or humerus. The humeral componenttypically has an elongated intramedullary stem which is utilized tosecure the humeral component to the patient's humerus. In such a totalshoulder replacement procedure, the natural glenoid surface of thescapula is resurfaced or otherwise replaced with a glenoid componentwhich provides a bearing surface for the head portion of the humeralcomponent.

Glenoid components have heretofore been designed which include a numberof plastic inserts coupled to metal backings The metal backings areprovided to secure the plastic inserts to the glenoid surface of thescapula. However, use of such two-piece glenoid components has a numberof drawbacks associated therewith. For example, it is possible over theuseful life of the glenoid component for the plastic inserts to separatefrom the metal backing thereby necessitating replacement of the glenoidcomponent. In addition, over time wear of the plastic insert inherentlyoccurs at the interface between plastic insert and the metal backing Itis possible for the plastic insert to wear to a degree whichnecessitates replacement of the glenoid component. It should beappreciated that in either case, such replacement of the glenoidcomponent requires the patient to again be subjected to a surgicalprocedure and the subsequent recovery period associated therewith.

In response to the shortcomings associated with two-piece glenoidcomponent designs, a number of one-piece glenoid components haveheretofore been designed. In regard to such one-piece designs, a bodyportion, having a bearing surface defined therein for receiving the headof the humeral component, has a number of attachment pegs integrallyformed therewith. The attachment pegs are advanced and thereaftersecured into a corresponding number of holes which are drilled in theglenoid surface of the scapula by use of bone cement. An example of sucha one-piece glenoid component that is designed to be secured to thescapula by use of bone cement is disclosed in U.S. Pat. No. 5,032,132issued to Matsen, III et al.

As with the two-piece designs, certain one-piece glenoid componentswhich have heretofore been designed have a number of drawbacksassociated therewith. For example, some studies have speculated that itmay be desirable to secure artificial components to natural bonestructures without the use of bone cement. Glenoid components which havebeen designed to be secured to the scapula by the use of bone cementgenerally cannot be secured to the natural glenoid without use of thesame.

Many glenoid component designs have been manufactured to addressdifferent types of scapular deficiencies. For example, some glenoidcomponents have anchor pegs with flexible fins that are designed to actas barbs when inserted into the scapula. Other designs may utilizeglenoid components with a buttress extending from the glenoid to filllarger defects in the natural glenoid. These may also include anchorand/or stabilizing pegs. In other embodiments a vault-filling glenoidmay be used to fill a natural glenoid that has severe defects.

However, one problem with even existing modular designs, is that they donot provide the surgeon with the option of using different designs oncesurgery has started. Also, if a kit was to include all the differentsizes and variations, the kit would be quite large and cumbersome tobring into surgery.

Another problem is that glenoid bone quality and surface deteriorationvaries significantly from patient-to-patient. Therefore, in currentdesigns, having standard peg or buttress or vault locations may not workwith specific patients' anatomy. Furthermore, in some embodiments, thesurgeon may choose a medial-lateral approach. In that approach, it maybe difficult to fit posts and vaults that are designed to be insertedfrom an overhead position.

SUMMARY

According to one embodiment of the present invention, a kit for makingglenoid prosthesis is provided. The kit includes an articulating memberhaving an articulation side and an opposing second side opposing thearticulating member. The opposing second side includes a lockingmechanism. The kit further includes a plurality of bases. Each of theplurality of bases has an articulating-member facing side and a glenoidattachment side. Each of the plurality of glenoid attachment sidesincludes at least one glenoid attachment member extending outwardly andis sized and shaped to extend into a patient's glenoid. The glenoidattachment member of one of the plurality of bases differs from theglenoid attachment member of at least one other of the plurality ofbases. Each of the plurality of bases includes a locking mechanism sizedand shaped to lock each of the plurality of bases to the articulatingmember.

According to another embodiment of the present invention, the method ofassembling a glenoid assembly is provided. A base is selected from aplurality of bases. At least one of the plurality of bases has a sizedifferent than a size of one of the other of the plurality of bases. Theselected base is coupled to an articulating member. The selected base islocked to the articulating member via a locking mechanism.

According to yet another embodiment of the present invention, a kit formaking glenoid prosthesis is provided. The kit includes an articulatingmember having an articulation side and an opposing second side opposingthe articulating member. The opposing second side includes a lockingmechanism. The kit further includes a plurality of bases, and each ofthe plurality of bases has an articulating-member facing side and aglenoid attachment side. Each of the plurality of glenoid attachmentsides differs from the glenoid attachment side of at least one other ofthe plurality of bases. Each of the plurality of bases includes alocking mechanism sized and shaped to lock each of the plurality ofbases to the articulating member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a glenoid assembly according to oneembodiment of the present invention.

FIG. 2 is a perspective view of a base of the glenoid assembly of FIG.1.

FIG. 3 is a perspective view of an articulating member of the glenoidassembly of FIG. 1.

FIG. 4 is a perspective view of the modular glenoid assembly of FIG. 1positioned between a glenoid surface of a scapula and a humeralcomponent.

FIG. 5 is a perspective view of a glenoid assembly according to anotherembodiment of the present invention.

FIG. 6 is an illustration showing a kit for making a modular glenoidassembly according to one embodiment of the present invention.

FIG. 7 is an illustration of a base of the glenoid assembly according toanother embodiment of the present invention.

FIG. 8 is a flow chart illustrating a method for assembling the modularglenoid assembly according to one embodiment of the present invention.

Additional features of the present invention will become apparent tothose skilled in the art upon consideration of the following detaileddescription of preferred embodiments exemplifying the best mode ofcarrying out the invention as presently perceived.

DETAILED DESCRIPTION OF THE DRAWINGS

A modular glenoid assembly 10 is provided in accordance with the presentinvention. FIG. 1 shows glenoid assembly 10 including a base 12 and anarticulation member 14. The base 12 and articulation member 14 arelocked in a fixed relationship. As shown in FIGS. 1 and 2, the base 12includes a first side 16 and a second side 18. The first side 16includes a finned anchor peg 20 and a cemented peg 22 sized and shapedto attach to a glenoid as will be described further below. Although inthis embodiment the base 12 includes a single finned anchor peg 20 and asingle cemented peg 22, it should be understood that in otherembodiments, there may be differing numbers of pegs 20, 22. Furthermore,the base 12 may include other types of attachment members such as pins,screws, wedge-shaped fillers, spikes. The second side 18 of the base 12is generally flat and is sized and shaped to abut the articulationmember 14.

The base 12 also includes locking features 24. The locking features 24in the embodiment illustrated in FIGS. 1 and 2 include a locking recess26 and a pair of locking protrusions 28. These will be described belowin further detail.

Turning now to FIGS. 1 and 3, the articulation member 14 will be furtherdescribed. The articulation member 14 includes an articulation side 30and an attachment side 32. The attachment side 32 is sized and shaped toreceive the second side 18 of the base 12. The attachment side 32includes an opening 34 defined on three sides by walls 36 of theattachment side 32. The fourth side is open, to allow the base 12 toslide into the articulating member 14. The top of the three walls 36 mayinclude a lip 38 that extends out into the recess 34. The lip 38 exertspressure against the base 12 and keeps the base from falling out of thearticulating member 14.

The articulating member 14 further includes locking features 40 sizedand shaped to engage the locking features 24 of the base 12. As shown inthis embodiment, the locking features 40 include a pair of wall recesses42. The pair of wall recesses 42 engages the pair of locking protrusions28 of the base 12 (FIG. 2) so as to lock the base 12 to the articulatingmember 14. As the base 12 is slid in through the open side 38, thelocking protrusions 28 will snap lock into place in the recesses 42. Inthis embodiment, the locking features 24 of the base 12 also includesthe locking recess 26 that corresponds to a projection 44 in thearticulating member 14. The projection 44 extends out into the recess 34of the articulation member 14 and engages the locking recess 26 in asnap-locked configuration. Other types of locking arrangements such astapers, locking rings, and other known locking mechanisms may be used.

Turning now to FIG. 4, the glenoid assembly 10 is shown with respect toa humerus 46 and a scapula 48. Glenoid assembly 10 is designed to beattached to glenoid surface 49 of scapula 48 to replace the naturalglenoid surface. As shown, the finned anchor peg 20 and cemented peg 22correspond to holes 50 drilled into the glenoid surface 49. The finnedanchor peg 20 and cemented peg 22 will be placed in the holes 50,locking the glenoid assembly 10 to the glenoid surface 49.

The articulation side 30 of the articulation member 14 is smooth andwill articulate with the head portion 52 of the humeral component 46. Insome embodiments, the head portion 52 may also be an implant. In otherembodiments, the head portion 52 may be the natural humeral head.

FIG. 4 illustrates an embodiment in which the glenoid assembly 10 isassembled prior to the glenoid assembly 10 being implanted into theprepared glenoid 49. However, in other embodiments, the prepared glenoid49 may be prepared as described above. Then, the base 12 is insertedinto the holes 50 of the prepared glenoid 49. The opening 34 of thearticulating member 14 is then slid onto the base 12, locking the base12 and the articulating member 14.

Turning now to FIG. 5, another embodiment of the present invention isillustrated. In this embodiment, a glenoid assembly 60 includes a base62 and an articulating member 64. A modular glenoid assembly 60 isprovided in accordance with the present invention. FIG. 5 shows glenoidassembly 60 including a base 62 and an articulation member 64. The base62 and articulation member 64 are locked in a fixed relationship. Asshown in FIG. 5, the base 62 includes a first side 66 and a second side68. The first side 66 includes a wedge-shaped filler 70 sized and shapedto attach to a glenoid. Similar to how was described in the previousembodiment, a glenoid is prepared to fit the wedge-shaped filler 70.Although in this embodiment the base 62 includes a wedge-shaped filler70, it should be understood that in other embodiments, there may beother attachment-type mechanisms, such as cemented pegs, finned anchorpegs, pins, screws, and/or spikes. The second side 68 of the base 62 isgenerally flat and is sized and shaped to abut the articulation member14.

The base 62 also includes locking features 72. The locking features 72in the embodiment illustrated in FIG. 5 include a recess 73 defined bythe wedge-shaped filler 70 and a lip 74 that extends outwardly. Therecess 73 and lip 74 will be described further below.

Turning now to the articulation member 64, the articulation member 64includes an articulation side 76 and an attachment side 78. Theattachment side 78 is sized and shaped to receive the second side 68 ofthe base 62. The attachment side 78 includes an opening 80 defined ontwo sides by walls 82 of the attachment side 78. The other two sides 84oppose one another and are open, to allow the base 62 to slide into thearticulating member 64. The top of the two walls 82 may include aprojection 86 that extends out into the recess 73. The projection 86exerts pressure against the base 62 and keeps the base from falling outof the articulating member 64. In use, the base 62 is slid into one ofthe open sides 84 and the lip 74 engages the side walls 82, while theprojection 86 fits within the recess 73 of the base 62. In someembodiments, there may be three side walls 82, not just two and only oneopen side 84. Also, other types of locking arrangements such as tapers,locking rings, and other known locking mechanisms may be used.

Turning now to FIG. 6, a kit 100 for modular glenoid prosthesis isshown. The kit includes an articulating member 102 and a plurality ofbases 104. The articulating member 102 includes an articulating side 106and an opposing second side 108. The opposing second side includes alocking mechanism 110. In this embodiment, the locking mechanism 110 isthe same as that described in FIGS. 1-4. In other embodiments, thelocking mechanism 110 may be of the same type as described in FIG. 5.

The plurality of bases 104 includes a pegged base 112 and a wedge-shapedfiller base 114. Each of the plurality of bases 104 have anarticulating-member facing side 116 and a glenoid attachment side 118,which includes at least one glenoid attachment member 120 extendingoutwardly and sized and shaped to extend into a patient's glenoid. Thepegged base 112 has a glenoid attachment member 120 that includes afinned anchor peg 122 and a cemented peg 124. The wedge-shaped fillerbase 114 includes a glenoid attachment member 120 that is a wedge-shapedfiller 126. Other glenoid attachment members 120 may also be included,such as screws, pins, spikes, and other numbers of pegs 122, 124. Eachof the plurality of bases 104 also includes a locking mechanism 128. Thelocking mechanism 128 is of the type described in FIGS. 1-4. In otherembodiments, the locking mechanism may be of the same type as describedwith respect to FIG. 5.

Turning now to FIG. 7, another embodiment of the present invention willbe shown. In this embodiment, a modular base 130 is included. Themodular base 130 includes a support base 132 and a plurality of glenoidattachment members 133. The support base 132 includes attachmentmechanisms 134. In this case, the attachment mechanisms 134 aregenerally spherical recesses. The glenoid attachment members 133 alsoinclude attachment mechanisms 136. In this embodiment, the attachmentmechanisms are generally spherical shaped balls that lock into therecesses on the support base 132. Other types of attachment mechanismsmay be used. Also, any number and type of glenoid attachment members 133may be included, such as wedge-shaped fillers, screws, pins, spikes, andother numbers and types of pegs. The base 130 will lock into anarticulating member 14, 64, 102 as described above in reference to FIGS.1-6.

All of the pieces described above may be made of polyethylene, such asultrahigh molecular weight polyethylene. Other biocompatible plasticsmay also be used. In some embodiments, biocompatible metals may also beused. In other embodiments, some of the parts, such as the articulationmember may be made of biocompatible metal while other parts, such as thebase may be made of biocompatible plastics. In other words, anycombination of biocompatible plastics and/or metals may be used.

Turning now to FIG. 8, a method for using a modular glenoid according toone embodiment of the present invention will be described. First, atstep s200, a base is selected from a plurality of bases. Then, at steps202, the selected base is inserted into the prepared glenoid. Anarticulating member is then slid into the base, locking the articulatingmember to the base (step s204).

1. The method of assembling a glenoid assembly, the method comprising:selecting a base from a plurality of bases, wherein at least one of theplurality of bases has a size different than a size of one of the otherof the plurality of bases; coupling the selected base to an articulatingmember; and locking the selected base to the articulating member via alocking mechanism.
 2. The method of claim 1, wherein the lockingmechanism includes a lip on one of the selected base and thearticulating member and a recess on the other of the selected base andthe articulating member.
 3. The method of claim 1, wherein the lockingmechanism includes a pair of protrusions on one of the selected base andthe articulating member and a pair of recesses on the other of theselected base and the articulating member.
 4. The method of claim 1,further comprising inserting the selected base into a prepared glenoid.5. The method of claim 4, wherein the inserting the selected base intothe prepared glenoid is performed before the selected base is coupled tothe articulating member.